Liquid storage tank



Jan. 16, 1951 c. ARNE LIQUID STORAGE TANK 2 Sheets-Sheet 1 Filed Sept.18, 1946 Jan. 16, 1951 c, ARNE 2,537,954

LIQUID STORAGE TANK Filed Sept. 18, 1946 2 Sheets-Sheet 2 Patented Jan.16, 1 951 UNITED STATES PATENT OFFICE LIQUID TANK Christian Arne,Chicago, 111., assignorto Chicago Bridge :85 Iron Company, a corporationof Illinois Application September 18, 1946, "Serial No. 697,7 39

3 Claims.

This invention relates to liquid storage tanks, and more particularly toliquid storage tanks having a variable volumetric vapor capacity.

In storage tanks for volatile liquids, such :as gasoline, provision mustbe made for the varying volume of volatilized vapor caused by changes intemperature, etc. It has been customary in many installations to providea. separate vessel to receive expanding vapors from the storage tank,and to return the vapors to the storage tank upon their contraction dueto a decrease in temperature or otherwise- Other installations providefor a rising and falling lifter roof.

I have invented, and am herein disclosing and claiming, a storage tankhaving a flexible nonmetallic roof thereover, which is adapted to riseand fall with increases and decreases of vapor pressure within the tankso as to allow breathing of the vessel. The flexible breather roof beingalso the weather roof over the tank elimihates the necessity ofproviding a metallic weather roof over the tank and also eliminates thenecessity of a separate breather or vapor vessel.

The invention will be described as embodied in the accompanying drawingsin which Fig. 1 is a top elevation, partly broken away, of a storagetank having a breather roof thereover;

Fig. 2 is a vertical section along lines 2-2 of Fig. 1;

Fig. 3 is a top elevation of a slightly modified form of roof, and

Fig. 4 is a vertical section along lines 4-4 of Fig. 3.

Referring more particularly to Figs. 1 and 2, I show a storage tank Ibeing generally cylindrical in shape having a flexible non-metallicweather roof II secured to the sides of the shell at I2. The flexibleroof is in the form of an annulus, and is secured at its inner peripheryto a dished metallic member I3 having a central drain opening I4therein. Communicating with the opening I 4 is a vertical pipe I5extending downwardly into the interior of the tank where it is receivedby an upstanding vertical pipe I6 of somewhat larger diameter. Near thelower portion of the pipe I6 is a drain pipe I! to the exterior of thetank. Moisture falling or condensing upon the roof and the dishedmetallic portion I3 is conveyed by means of the drain pipes justdescribed to the exterior of the tank. The drain pipes also aid inkeeping the roof centered. The entire roof, comprising the portions IIand I3, is free to flex upwardly and downwardly with variations in vaporpressure within the tank,

:2 and the :roof is supported at its lowest position by girders I-Battached atone end to the side :of the tank and at the dinner ends tothe drain pipe I6.

A somewhat similar embodiment is shown in Figs. :3 and 4 to whichsimilar reference numerals have been added idifl ering by an even onehundred. The :roof in the embodiment shown in Figs. 3 and A isreinforced by :a spiral metallic member I I9 which spirals inwardly fromthe outer portion of the roof to the inner portion. In its lowestposition, the metallic reinforcing member rests upon the girders I I8and the spiral form permits drainage to the central drain pipe II I whenthe roof is in its lowest position. The drain pipe I I I is providedwith a trap I20 in order to retain liquid I2I within the lower portionof the drain pipe I I6 at all times. The liquid so retained serves notonly to seal the connection between the drain pipes I I5 and IIB, butalso serves as a pressure and vacuum venting means. Should the vaporpressure within the tank exceed a predetermined limit, the vapor willforce the liquid I2I some of the distance upwardly in the pipe H5 andthence escape, while excessive vacuum within the tank when the roof isin its lowest position would draw air in through the vents and throughthe liquid. The upper limits of pressure and vacuum desired within thetank may be predetermined by the locationof the entrance of the drainpipe I20 into the drain pipe IIB.

While I have shown and described certain embodiments of my invention, itis to be understood that it is capable of many modifications. Changes,therefore, in the construction and arrangement may be made withoutdeparting from the spirit and scope of the invention as disclosed in theappended claims.

I claim:

1. A liquid storage tank comprising a shell and a flexible weather roofthereover, said roof being adapted to flex upwardly and downwardly withchanges of vapor pressure within the tank to provide a variablevolumetric vapor capacity for said tank, said roof comprising an annularnonmetallic flexible member attached to the shell at its outer peripheryand at its inner periphery to a substantially circular metallic member,said roof being reenforced by a metallic member attached to said roof,said metallic member being in the form of a spiral commencing at theouter portion of the roof and terminating adjacent the inner portionthereof, said circular member having an opening in its centercommunicating with a vertical drain pipe upstanding from the bottom ofsaid tank, and support means within the tank for supporting said roof inits lowest position.

2. A liquid storage tank comprising a shell and a flexible weather roofthereover, said roof having a circular dished metal central portion andan outer annular fabric portion and being adapted to flex upwardly anddownwardly with changes of vapor pressure within said tank to provide avariable volumetric vapor capacity for said tank, said roof beingprovided with a vertical drain pipe in the center of the metal portionand extending a part of the distance toward the bottom of said tank, andsaid tank having an upstanding vertical drain pipe extending a part ofthe distance toward said roof, said downwardly extending drain pipebeing slidably received in said upwardly extending drain pipe, anexhaust pipe communicating with the exterior of the tank and connected 4a flexible fabric weather roof thereov'er, said roof being adapted toflex upwardly and downwardly with changes of vapor pressure within saidtank to provide a variable volumetric vapor capacity for said tank, aninwardly dished metallic member at the center of the roof attached tothe flexible roof at its outer edge and having an opening at its centercommunicating with a vertical drain pipe extending downwardly into theinterior of the tank and into an upstanding Vertical pipe of largerdiameter than said first mentioned pipe positioned within the tank,means for maintaining water in the upstanding pipe at all times, andsupporting means within said tank-for supporting said roof in its lowestposition. CHRISTIAN ARNE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

